Combination electric plug and socket



Get. 3, 1950 g, F, GRILL COMBINATION ELECTRIC PLUG AND socxm'r Filed Aug. 3,, 1949 CHARL 5 7. GR/LL v I v H W (Ittorneg Patented Oct. 3, 1950 .UNITED STATES PATENT OFFICE COMBINATION ELECTRIC PLUG AND SOCKET Charles T. Grill, Pasadena, Calif.

Application August 3, 1949, Serial No. 108,405

6 Claims. 1

This invention relates to a combination electric plug and socket.

An object of the present invention is to provide a combination plug and socket in which the former is readily inserted to make electrical connection with the latter Without the need of seeking out an oriented entry position for the contact prongs of the plug, the structure contemplating that the prongs may have any angular position with respect to the contacts of the plug and yet at all times finding proper engagement with said contacts. Thus, even in the dark, the plug may readily be connected to the socket.

Another object of the invention is to provide a combination plug and socket that interlocks to obviate inadvertent extraction of the plug.

Another object of the invention is to provide a combination device, as indicated, that is characterized by safety in that the contacts in the socket are so concealed or recessed that bridging thereof by the fingers or by metallic objects is rendered so dimcult as to be practically incapable of occurrence.

The invention also has for its objects to provide such means that are positivein operation, convenient in use, easily installed in a working position and easily disconnected therefrom, economical of manufacture, relatively simple, and of general superiority and serviceability.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description. However, the drawings merely show and the following description merely describes one embodiment of the present invention, which is given by way of illustration or example only.

In the drawings, like reference characters designate similar parts in the several views.

Fig. 1 is a longitudinal sectional view of a combined plug and socket according to the present invention, the view being taken on the planes of line ll of Fig. 2.

Fig. 2 is a front elevational view of the socket, the mounting brackets therefor being partly broken away.

Figs. 3 and 4 are cross-sectional views taken substantially on the respective lines 33 and i-4 of Fig. 1.

Fig. 5 is an inner face view of one socket body part, the socket body comprising two such parts.

. The device that is illustrated comprises a socket in and a plug II. The former is so formed and proportioned that the same may be operatively mounted inthe same manner as conventional sockets, either singly or in pairs, and in conventional outlet boxes and covered by conventional face plates. Means, such as brackets l2, are employed for effecting mounting of the socket in an outlet box and said brackets, conventionally, may mount a suitable face plate.

The socket It comprises, generally, a die1ectric body l3, a pair of electric terminals i l within said body, a closure member ii for an openended socket chamber I6 formed in the body, and resilient means such as a compression sprin ll for engaging said closure member to close the open end of socket chamber 66.

The body l3 comprises two identical body parts 18, as best seen in Fig. 5, that are held together as by screws I9 which also fasten brackets 12 in place. The two-part body facilitates manufacture, but for the purposes of this disclosure, the body will be treated as an integral member, i. e., as if it were not split.

The socket chamber 46, at its open end, is outwardly flared to provide a lead-in throat 20, the opposite end of said chamber being closed by a wall 21. Two pairs of opposed recesses 22 are formed in the otherwise cylindrical wall of chamber i6, said four recesses being equally spaced and all alike. Each recess, on one side, is gradually blended into said cylindrical wall and, on the opposite side, is provided with a generally radial shoulder 23, said shoulder being on the same side of each respective recess. The inner ends of said recesses are formed to gradually blend, as at 24, into the cylindrical wall of chamber 16. The outer end of each recess terminates in a transverse shoulder 25 adjacent throat 20. While four recesses 22 are disclosed, it will be evident that any suitable even number may be provided, such as two, four, six or eight.

The two terminals M are arranged on opposite sides of body it and may be embedded as inserts therein when the body parts are molded. Since there are four recesses, each terminal i4 is formed to have two similar contacts 26', said contacts branching from a main part 2'3 extending to the closed end of the body. The latter part terminates in a connection flange 28 for an electrical conductor. One contact 25 of one terminal I4 is arranged to be diametrically opposite a contact of the other terminal. I

The end of each contact 26 is formed as a transversely curved U-shaped portion to provide a seat 2 9, the open side of which is directed to- Ward the inner end of socket l3. end of each recess 22 is open to communicate with each respective seat. Since the contacts 26 are The forward to guide the plug into socket chamber l6.

located between shoulders 25 and the throat 20, it will be seen that the same are not within reach of any objects that may be introduced into socket chamber it, unless, as will be later described, such objects first fall laterally into recesses 22 and then are drawn forward to engage said contacts.

The closure member i comprises a dielectric disc 30 that has a sliding fit in socket chamber l8. Said disc is provided with oppositely disposed lateral projections 3! that extend in a rearward direction and are engaged in grooves or slots 32 formed in the cylindrical wall of chamber IS. The forward or outer position of disc 36 is limited by said lateral projections 3i engaging shoulders to locate said disc just rearward or inward of throat 2G. The rearwardmost position of said disc is limited by engagement of projections 31 and wall 2|. Compression spring ll normally projects disc to its outer position, thus closing socket chamber H5.

It will be apparent that the above described socket iii is safe against inadvertent bridging of its contacts; that dust is excluded from the interior thereof by the closure member l5; and that by endwise retraction of the latter member, the contacts M are adapted to be electrically engaged. To the latter end, the novel plug H is provided,

Plug ll comprises, generally, a body 35, a pair of prong terminals 36,, and suitable conductors 3'l-one for each prong.

The body 35, in this case, is shown as com-- prising a cylindrical plug part 38 of dielectric material and a larger end part 39 into which plu part 38 is fitted, the latter also being of dielectric material. Thetwo parts are inter-fixed and may be separable for convenience of assembly of the plug.

Plug part 38 has a rounded end 40 for convenient insertion past throat 20 into socket chamber I5 of the socket it and freely slidingly fits into said chamber. Two longitudinal passages 4| are formed in part38, the same terminating short of end M3 and opening laterally, as at 42, on opposite sides of said plug part. A wall 43 separates passages 4i,

Prongs 36 each comprise an elongated metal stripfi i that is connected to one of the conductors 31. Said strips extend through passages 4| which are oi a cross-sectional size to permit free fiexure ofsaid strips. Each strip M, at its end adjacent theend 40 of plug part 38, is formed with a laterallydirected hook 45, said hooks extending outwardly through openings 42. When unflexed, said hooks extend beyond the peripheral face of plug part 38.

When the plug II is to be inserted into socket ID, the former is held to present its rounded end toward closure member l5. Such presentation need only be approximately aligned, since throat 20, together with the round of end 60, will serve The angular orientation of prong hooks 45 is immaterial, said hooks merely being pressed inward by fiexure of the prongs until the free ends thereof slide against the cylindrical wall of socket chamber l6.

As the plug is pushed further into the socket, displacing closure member l5 inward, if, by chance, hooks 45 are exactly aligned with two opposite contacts 26, said hooks will slip past shoulder 25 and the prongs will spring outward. Now, a pull on the plug will bring the hooks into firm engagement with seats 29. of said contacts 26. However, in most cases, such exact alignment of hooks and contacts will not occur. Under such initial misalignment, hooks 45 will be held retracted by the cylindrical wall of the socket chamber. It is now only necessary to rotate the plug, that amount which will bring the hooks 45 into alignment with any two opposite recesses 22 and said hooks will spring into said recesses. This rotation is limited by radial shoulders 23 of said recesses. Now, a pull on the plug will electrically engage the prong hooks and the contacts 25 that are at the ends of said recesses. It will be seen that not more than a quarter turn of the plug and, in the majority of cases, a shorter turn, is needed to effect proper connection of plug and socket and that, once connected, the plug cannot be pulled out.

Disconnection is simple. The plug is first pushed inward, as limited by projections 3|, then rotated in the opposite direction (away from shoulders, 23) to cam the hooks inward as they ride from their recesses back into engagement with the cylindrical wall of the socket chamber. Now, the plug can be pulled straight out. Closure member [5 follows to close off the chamber.

While the invention that has been illustrated and described is now regarded as the preferred embodiment, the construction is, of course, subject to modifications without departing from the spirit and scope of the invention. It is therefore not desired to restrict the invention to the particular form of construction illustrated and described, but to cover all modifications that may fall within the scope of the appended claims.

Having thus described the invention, what is claimed and desired to be secured by Letters Patent is:

1. In a combined plug and socket, a plug having a cylindrical body, a pair of flexible prong terminals in said body, a hook on the end ofv each of said terminals and normally extending laterally beyond said body, a socket having an open-ended cylindrical chamber receptive of the plug body, there being opposed recesses in the wall of said chamber, said recesses, on one side, gradually blending into the wall of the chamber and, on the other side, terminating in a radial shoulder, said plug prongs being contractable by engagement of the hooks thereof with said chamber wall, during insertion of the plug, and then expandable into said opposed recesses by rotation of the plug relative to the socket until said hooks are engaged with the mentioned radial shoulders, and a pair of terminals carried by the socket and each provided with a contact located in the mentioned recesses and having hooking engagement with the hooks of the plug terminals while said hooks are held aligned with the mentioned recesses. by said radial shoulders.

2. In a combined plug and socket, a plug having a cylindrical body, a pair of flexible prong terminals in said body, a hook on the end of each of said terminals and normally extending laterally beyond said body, a socket having an open-ended cylindrical chamber receptive of the plug body, there being opposed recesses in the wall of said chamber, said recesses, on one side, gradually blending into the wall of the chamber and, on the other side, terminating in a radial shoulder, said plug prongs being contractable by engagement of the hooks thereof with said chamber wall, during insertion of the plug, and then expandable into said opposed recesses by rotation of the plug relative to the socket until said hooks are engaged with thementioned terminals in said body, a hook on the end of I each of said terminals and normally extending laterally beyond said body, a socket having an open-ended cylindrical chamber receptive of the plug body, there being opposed recesses in the wall of said chamber, said recesses, on one side, gradually blending into the wall of the chamber and, on the other side, terminating in a radial shoulder, said recesses, on the ends thereof adjacent the open end of the socket chamber, each terminating in a transverse shoulder, said plug prongs being contractable b engagement of the hooks thereof with said chamber wall, during insertion of the plug, and then expandable into said opposed recesses by rotation of the plug relative to the socket until said hooks are engaged with the mentioned radial shoulders, and a pair of terminals carried by the f:

the mentioned recesses by said radial shoulders,

the mentioned transverse shoulders overstanding said contacts and spacing the latter from the socket chamber.

4. In a combined plug and socket, a plug having a cylindrical body, a pair of flexible prong terminals in said body, a hook on the end of each of said terminals and normally extending laterally beyond said body, a socket having an open-ended cylindrical chamber receptive of the plug body, there being opposed recesses in the wall of said chamber, said recesses, on one side, gradually blendin into the wall of the chamber and, on the other side, terminating in a radial shoulder, said recesses, on the ends thereof adjacent the open end of the socket chamber, each terminating in a transverse shoulder, said plug prongs being contracta-ble by engagement of the hooks thereof with said chamber wall, during insertion of the plug, and then expandable into said opposed recesses by rotation of the plug relative to the socket until said hooks are engaged with the mentioned radial shoulders, a pair of terminals carried by the socket and each provided with a contact located in the mentioned recesses and having hooking engagement with the hooks of the plug terminals while said hooks are held aligned with the mentioned recesses by said radial shoulders, the mentioned transverse shoulders overstanding said contacts and spacing the latter from the socket chamber, and a resiliently-urged closure member normally closing the end of the socket chamber that is forward of the mentioned transverse shoulders, said closure member having lateral projections adapted to engage said transverse shoulders to limit the outward movement of said member, said member being inwardly displacen havin a pair of resilient prong terminals each having a hook on its end, and said hooks being oppositely directed; a socket comprising a housing formed of two identical body parts, each body part having an open-ended semi-cylindrical socket chamber and the Wall of said chamber having at least one recess formed therein, said recess blending into said Wall at one side and at that end which is opposite to the open end of the chamber, the opposite side and end of said recess being respectively defined by a radial shoulder and a transverse shoulder, and a terminal carried by said body part and havin a hook-shaped contact disposed adjacent to the transverse shoulder of the recess and in spaced relation to the socket chamber, said plug being insertable into said chamber to bring the hooks on the ends of the prong terminals into hooking engagement with the hook-shaped contacts of the socket.

CHARLES T. GRILL.

REFERENCES CH'EED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

